Capacitance-type pressure sensor unit

ABSTRACT

A capacitance-type pressure sensor unit capable of being assembled without applying a pressure at an increased level to a circuit board. A connector body ( 6 ) has a base ( 6   b ) received in a peripheral wall section ( 13   b ) of a receiving casing ( 13 ) constituting a main body of the casing ( 13 ) and fixed to an end ( 13   e ) of the peripheral wall section ( 13   b ) by caulking. A pressure sensor element ( 3 ) constituted of a first insulating substrate ( 1 ) and a second insulating substrate ( 2 ) is arranged in a bottom wall section ( 13   a ) of the receiving casing ( 13 ) and a fluid chamber ( 15 ) into which pressure measured fluid is introduced is defined between a rear surface of the first insulating substrate ( 1 ) and the bottom wall section ( 13   a ). A circuit board ( 9 ) received in a circuit component receiving chamber ( 7 ) defined in the base ( 6   b ) of the connector body ( 6 ) is supported by connection conductors ( 8 ) for connection of a connector ( 5 ), metal terminal fitments ( 19 ) for electrically connecting output electrodes ( 2   c ) of the pressure sensor element ( 3 ) to a circuit board ( 9 ) and a ground terminal fitment ( 22 ) for electrically connecting a ground electrode of the circuit board ( 9 ) to the receiving casing ( 13 ) while being suspended in the chamber ( 7 ).

TECHNICAL FIELD

This invention relates to a capacitance-type pressure sensor unitadapted to measure a pressure based on a variation in capacitance.

BACKGROUND ART

First of all, a conventional capacitance-type pressure sensor unit whichis to be improved by the present invention will be described withreference to FIG. 14.

The capacitance-type pressure sensor unit shown in FIG. 14 includes afirst insulating substrate 1 having a front surface formed thereon withan electrode (not shown) and a rear surface acting as a pressure sensingsurface 1 a and a second insulating substrate 2 combined with the firstinsulating substrate 1 to constitute a pressure sensor element 3. Thesecond insulating substrate 2 has a rear surface provided thereon withan electrode (not shown) in a manner to be opposite to the electrode onthe first insulating substrate 1 while being spaced therefrom at apredetermined interval and a front surface 2 a provided thereon with afirst circuit pattern (not shown). The first circuit pattern iselectrically connected to the two above-described electrodes arranged inthe pressure sensor element 3. The second insulating substrate 2 ismounted thereon with at least one electric circuit component 4 bysoldering. The electric circuit component 4 is constituted by anintegrated circuit or the like and electrically connected to the firstcircuit pattern to carry out processing of an output of the pressuresensor element 3.

The capacitance-type pressure sensor unit also includes a connector 5arranged on a side of the front surface 2 a of the second insulatingsubstrate 2. The connector 5 includes a connector body or connectorhousing 6, which includes a base 6 b having an end surface 6 a keptcontacted with the front surface 2 a of the second insulating substrate2 of the pressure sensor element 3 and provided therein with a circuitcomponent receiving chamber 7 in which the electric circuit component 4is received. Also, the connector 5 includes a plurality of connectionconductors or connector terminals 8 which are supported in the connectorbody 6 and of which one end is arranged in the circuit componentreceiving chamber 7 and the other end is externally exposed.

The circuit component receiving chamber 7 of the connector 5 has acircuit board 9 arranged therein in a manner to be spaced at an intervalfrom the front surface 2 a of the second insulating substrate 2. Thecircuit board 9 is arranged in a manner to be interposedly supportedbetween an annular support 10 made of an electrically insulatingmaterial and arranged on an outer peripheral edge of the front surfaceof the second insulating substrate 2 a and a step 6 c formed on an innerperiphery of the base 6 b of the connector body 6. The circuit board 9is provided thereon with a second circuit pattern (not shown), which iselectrically connected to the first circuit pattern on the front surface2 a of the second insulating substrate 2 and the connection conductors 8of the connector 5. Connection between the connection conductors 8 andthe second circuit pattern on the circuit board 9 is carried out byinserting one end 8 a of each of the connection conductors 8 via each ofthrough-holes formed via the circuit board 9 and soldering the end to asoldering electrode arranged on a rear surface of the circuit board 9.The circuit board 9 and the first circuit pattern on the front surface 2a of the second insulating substrate 2 are electrically connected toeach other through electrical connection means 11 such as a flexibleprinted board or the like. The circuit board 9 thus connected is mountedthereon with electric circuit components 12 a and 12 b such ascapacitors or the like for removing noise intruding thereinto throughthe other end 8 b of each of the connection conductors 8 of theconnector 5 by soldering.

The pressure sensor element 3, the circuit board 9, the base 6 b of theconnector body 6 and the like are received in a receiving casing 13 madeof metal. The receiving casing 13 includes a bottom wall section 13 aformed with a fluid inlet port 14 through which pressure measured fluidsuch as gas, liquid or the like of which a pressure is to be measured isintroduced into the capacitance-type pressure sensor unit of theillustrated embodiment. The receiving casing 13 also includes aperipheral wall section 13 b connected at one end thereof to the bottomwall section 13 a, a cylindrical section 13 c mounted on a centralportion of the bottom wall section 13 a so as to surround the fluidinlet port 14 and a threaded section 13 d formed on an outer peripheryof a distal end of the cylindrical section 13 c. The pressure sensorelement 3 is received in the peripheral wall section 13 b of thereceiving casing 13 in such a manner that the pressure sensing surface 1a is arranged opposite to the bottom wall section 13 a and so as not todefine a large gap between the pressure sensing surface 1 a and theperipheral wall section 13 b. The pressure sensing surface 1 a of thepressure sensor element 3 and the bottom wall section 13 a are arrangedso as to define a fluid chamber 15 therebetween into which the pressuremeasured fluid is introduced. The peripheral wall section 13 b has aseal member 16 arranged on a portion of an inner periphery thereofpositioned between the pressure sensing surface 1 a and the bottom wallsection 13 a. The seal member 16 is constituted by an O-ring for sealingthe fluid chamber 15. Also, a seal member 17 is interposedly arrangedbetween the base 6 b of the connector body 6 and the peripheral section13 b of the receiving casing 13. The seal member 17 is constituted by anO-ring supported in a groove formed on an outer periphery of the base 6b. The connector 5 is fixed on the receiving casing 13 by holding thebase 6 a of the connector body 6 in an upper end section 13 e of thereceiving casing 13 by caulking.

In the conventional capacitance-type pressure sensor unit thusconstructed, when pressure measured fluid such as gas, liquid or thelike is introduced through the fluid inlet port 14 into the fluidchamber 15, a pressure of the fluid acts on the pressure sensing surface1 a of the first insulating substrate 1 of the pressure sensor element3. Action of the pressure on the surface 1 a permits a variation incapacitance between the electrodes arranged opposite to each other inthe pressure sensor element 3. Such a variation in capacitance isconverted into a voltage signal by a signal processing circuitconstituted of the electronic circuit component 4 or the like. Thevoltage signal thus obtained is then outwardly transmitted through theconnector 5.

DISCLOSURE OF INVENTION

In the conventional capacitance-type pressure sensor unit constructed asdescribed above, the circuit board 9 is interposedly arranged betweenthe support 10 and the step 6 c provided on the inner periphery of thebase 6 b of the connector body 6. The support 10 is supported on thefront surface 2 a of the second insulating substrate 2 of the pressuresensor element 3 and the pressure sensor element 3 is supported throughthe O-ring 16 on the bottom wall 13 a of the receiving casing 13. Suchconstruction of the conventional capacitance-type pressure sensor unittends to cause a pressure of an increased magnitude to be applied to thecircuit board when the base 6 b of the connector body 6 is mounted inthe end 6 d of the receiving casing 13 by caulking. Such application ofan increased pressure to the circuit board may possibly cause damage tothe circuit board.

Also, the conventional capacitance-type pressure sensor unit is soconstructed that electrical connection between the circuit board 9 andthe first circuit pattern on the front surface 2 a of the secondinsulating substrate 2 is carried out using the electrical connectionmeans 11 such as a flexible printed board or the like. Unfortunately,such electrical connection causes an increase in manufacturing cost ofthe unit.

Accordingly, it is an object of the present invention to provide acapacitance-type pressure sensor unit which is capable of beingassembled without applying an increased pressure to a circuit board.

It is another object of the present invention to provide acapacitance-type pressure sensor unit which is capable of beingsimplified in structure and reduced in manufacturing cost.

In accordance with the present invention, a capacitance-type pressuresensor unit is provided which is constructed so as to solve theabove-described problem of the prior art. The capacitance-type pressuresensor unit generally includes a capacitance-type pressure sensorelement, a receiving casing, a circuit board and a connector. Thecapacitance-type pressure sensor element includes a first insulatingsubstrate which is made of an insulating material and has a frontsurface provided thereon with a first capacitance detecting electrodepattern and a rear surface constituting a pressure sensing surface and asecond insulating substrate which is made of an insulating material andfixed with respect to the first insulating substrate and has a rearsurface provided thereon with a second capacitance detecting electrodepattern in a manner to be opposite to the first capacitance detectingelectrode pattern while being spaced at an interval therefrom. Thecapacitance-type pressure sensor element functions to detect a variationin pressure acting on the pressure sensing surface of the firstinsulating substrate depending on a variation in capacitance between thefirst capacitance detecting electrode pattern and the second capacitancedetecting electrode pattern.

The receiving casing is made of metal and includes a cylindrical casingbody provided at one end thereof with an opening and at the other endthereof with a bottom wall section. The bottom wall section is providedwith a fluid inlet port through which a pressure measured fluid isintroduced into the receiving casing.

The circuit board includes a board member provided thereon with circuitpatterns and mounted thereon with at least a part of a plurality ofelectric circuit components constituting a signal processing circuit forprocessing an output of the pressure sensor element.

The connector includes a connector body which is made of an insulatingmaterial and includes a base formed on one surface thereof with anopening and provided therein with a circuit component receiving chamberfor receiving the circuit board therein in a manner to communicate withthe opening of the connector body. The connector also includes aplurality of connection conductors fixed in the connector body and eachhaving one end extending into the circuit component receiving chamberand electrically connected to each of the circuit patterns on thecircuit board and the other end externally exposed.

The circuit board has a component mounting surface arranged so as toextend along a front surface of the second insulating substrate of thepressure sensor element. More specifically, the pressure sensor elementis received in the casing body of the receiving casing so that a fluidchamber which fluid introduced through the fluid inlet port enters isdefined between the pressure sensing surface of the first insulatingsubstrate and the bottom wall section of the receiving casing.

The connector body is received in the casing body of the receivingcasing in such a manner that the base of the connector body ispositioned on a side of the opening of the receiving casing rather thanon a side of the pressure sensor element. More specifically, theconnector body is received in the casing body of the receiving casing insuch a manner that the base of the connector body is kept contacted atan end thereof on a side of the opening of the base with the frontsurface of the second insulating substrate of the pressure sensorelement. The receiving casing is securely mounted at an end thereofpositioned on a side of the opening of the connector body on the base ofthe connector body by caulking. The pressure sensor element and thecircuit patterns on the circuit board are electrically connected to eachother through a plurality of metal terminal fitments.

In the present invention, the circuit board is supported by at least oneof the connection conductors of the connector and the metal terminalfitments. Such construction prevents application of a pressure at anincrease level to the circuit board as encountered with the prior artduring caulking of the receiving casing. Also, the above-describedelectrical connection between the pressure sensor element and thecircuit patterns on the circuit board by means of a plurality of themetal terminal fitments permits electrical connection between thepressure sensor element and the circuit patterns to be positivelycarried out even when the circuit board is kept suspended in the circuitcomponent receiving chamber. In particular, when the circuit board issupported by at least the connection conductors of the connector andmetal terminal fitments, assembling of the pressure sensor unit isattained without applying a pressure at an increased level to thecircuit board while more firmly supporting the circuit board.

In a preferred embodiment of the present invention, the circuit patternsinclude a ground electrode connected to the receiving casing. When theground electrode and receiving casing are electrically connected to eachother through a ground terminal fitment made of metal, the groundterminal fitment is arranged so as to support the circuit board. Suchconstruction permits ground connection between the ground electrode ofthe circuit patterns and the receiving casing to be facilitated by meansof the ground terminal fitments. Also, the ground terminal fitmentsupports the circuit board, so that the circuit board may be suspendedlysupported in the circuit component receiving chamber with increasedstability.

In a preferred embodiment of the present invention, the metal terminalfitments each include a first section having one end connected to theelectrode included in the circuit patterns of the circuit board bysoldering and the other end fixed to a portion of a wall of theconnector body which surrounds the circuit component receiving chamberand is opposite to the circuit board, as well as a second section havingone end formed integrally with the first section and the other endconnected to each of output electrodes of the pressure sensor element bysoldering. The second section is preferably formed at a portion thereofbetween the one end thereof and the other end thereof into a shape whichpermits the second section to exhibit elasticity. The ground terminalfitment thus constructed permits the one end of the first section to beconnected to the electrode incorporated in the circuit patterns on thecircuit board by soldering and the other end thereof to be fixed on thewall of the connector body which surrounds the circuit board receivingchamber while being opposite to the circuit substrate. Also, the secondsection is integrated through the one end thereof with the first sectionand contacted at the other end thereof with the inner surface of thereceiving casing. Further, when the second section is formed at aportion thereof between the one end thereof and the other end thereofinto a shape which permits the second section to exhibit elasticity, theelasticity permits the other end of the second section to be stablyelectrically contacted with the inner surface of the receiving casing,so that assembling of the pressure sensor unit may be attained whilekeeping undue force from being applied to the connection between the oneend of the first section and the electrode on the circuit board,resulting in eliminating a failure in contact.

Also, in a preferred embodiment of the present invention, the firstinsulating substrate of the pressure sensor element is formed into acontour of a substantially circular shape in plan and the secondinsulating substrate of the pressure sensor element is formed on a sidewall section thereof with a flat section on which a plurality of outputelectrodes are arranged. Also, the second insulating substrate of thepressure sensor element is formed at a portion of the side wall sectionthereof opposite to the flat section with a recess in which the otherend of the ground terminal fitment is fitted. Thus, when the firstinsulating substrate of the pressure sensor element is formed into acontour of a substantially circular shape in plan, sealing between thefirst insulating substrate and the casing body of the receiving casingin the fluid chamber between the pressure sensing surface of the firstinsulating casing and the bottom wall section of the receiving casing isfacilitated. Also, the construction that the second insulating substrateof the pressure sensor element is formed on the side wall sectionthereof with the flat section on which a plurality of the outputelectrodes are arranged permits arrangement of a plurality of the outputelectrodes to be facilitated. Further, when the second insulatingsubstrate of the pressure sensor element is formed at a portion of theside wall section thereof opposite to the flat section with the recessin which the other end of the ground terminal fitment is fitted, theother end of the ground terminal fitment may be contacted with the innersurface of the receiving casing through the recess. Thus, the other endof the ground terminal fitment may be formed into any desired lengthwithout adversely affecting the pressure sensor unit.

In addition, in a preferred embodiment of the present invention, thecasing body of the receiving casing is formed on an inner surfacethereof with an annular casing-side step and the base of the connectorbody is formed on an outer periphery thereof with an annularconnector-side step, wherein the annular casing-side step andconnector-side step have a waterproof O-ring arranged therebetween whilekeeping the O-ring compressed. Such construction effectively preventsleakage of fluid from the inner surface of the casing body and the outerperiphery of the base of the connector body.

In a preferred embodiment of the present invention, the end of theconnector body is integrally provided with two or more projections andthe front surface of the second insulating substrate is formed with twoor more recesses in which the projections are fitted. This permitsrelative positioning between the connector body and the secondinsulating substrate of the pressure sensor to be positivelyaccomplished.

Also, in accordance with the present invention, a capacitance-typepressure sensor unit is provided. The pressure sensor unit generallyincludes a pressure sensor element, a connector, a circuit board and areceiving casing. The pressure sensor element includes a firstinsulating substrate having a front surface provided thereon with anelectrode and a rear surface acting as a pressure sensing surface and asecond insulating substrate which has a rear surface provided thereonwith an electrode in a manner to be opposite to the electrode on thefirst insulating substrate while being spaced at a predeterminedinterval therefrom and is combined with the first insulating substrate.A plurality of output electrodes are arranged on one of a front surfaceof the second insulating substrate and a side surface thereof andelectrically connected to the electrodes. Arrangement of the outputelectrodes on the front surface of the second insulating substrate maybe carried out by arranging a first circuit pattern on the front surfaceof the second insulating substrate and incorporating the outputelectrodes in the first circuit pattern. Also, at least one electriccircuit component for processing an output of the pressure sensorelement may be electrically connected to the first circuit patternprovided on the front surface of the second insulating substrate.

The connector includes a connector body which is made of an insulatingresin material and includes a base having an end surface contacted withthe front surface of the second insulating substrate of the pressuresensor element and provided therein with a circuit component receivingchamber for receiving the electric circuit component therein. Theconnector also includes a plurality of connection conductors supportedin the connector body and each having one end positioned in the circuitcomponent receiving chamber and the other end externally exposed.

The circuit board is arranged in the circuit component receiving chamberwhile being kept spaced from the front surface of the second insulatingsubstrate and includes circuit patterns electrically connected to theoutput electrodes on the front or side surface of the second insulatingsubstrate and the connection conductors. In this instance, when thefirst circuit pattern is arranged on the front surface of the secondinsulating substrate, the circuit pattern on the circuit boardconstitutes a second circuit pattern. In this instance, arrangement ofthe first circuit pattern on the front surface of the second insulatingsubstrate may be eliminated.

Electrical connection means are arranged so as to electrically connectthe circuit board on the circuit board and the output electrodes on thefront or side surface of the second insulating substrate to each other.

The receiving casing is made of metal and includes a bottom wall sectionformed with a fluid inlet port for introducing pressure measured fluidtherethrough and a peripheral wall section connected at one end thereofto the bottom wall section. The receiving casing receives the pressuresensor element and at least a part of the base of the connector bodytherein so that a fluid chamber which the pressure measured fluid entersmay be defined between the pressure sensing surface of the pressuresensor element and the bottom wall section.

The circuit board is supported on a circuit board support structurefixed on the second insulating substrate of the pressure sensor element.The circuit board support structure acts also as the electricalconnection means.

The construction of the present invention that the circuit board supportstructure is fixedly mounted on the second insulating substrate of thepressure sensor element to support the circuit board on the circuitboard support structure permits assembling of a pressure sensor unitwhich prevents application of a pressure at an increased level to thecircuit board as encountered with the prior art. Also, the constructionthat the circuit board support structure functions also as theelectrical connection means for electrically connecting the circuitboard and the output electrodes on the front surface of the secondinsulating substrate permits the pressure sensor unit to be simplifiedin structure and facilitates assembling of the unit, leading to areduction in manufacturing cost.

In this instance, the circuit patterns on the circuit board and theconnection conductors are preferably electrically connected to eachother through lead wires. This permits electrical connection between thecircuit board supported on the pressure sensor element through thecircuit board support structure and the connection conductorsincorporated in the connector by soldering or the like during assemblingof the pressure sensor unit to be facilitated by defining an interval ofa required size between the circuit board and the connection conductorsof the connector using lead wires of a required length.

In a preferred embodiment of the present invention, the circuit boardsupport structure is constituted by three or more metal terminalfitments each formed by subjecting a metal plate to machining, whereinthe terminal fitments each are provided at one end thereof with a firstconnection section which is fixed on the circuit board and connected toan electrode section included in the circuit patterns by soldering asrequired and at the other end thereof with a second connection sectionwhich is fixed with respect to the second insulating substrate of thepressure sensor element and connected to each of the output electrodesby soldering. Such construction of three or more such metal terminalfitments into the circuit board support structure facilitates assemblingof the circuit board support structure at a low cost. It is a manner ofcourse that a part of the three metal terminal fitments may not beconnected to the output electrodes.

When the circuit board support structure is constructed so as to act asthe electrical connection means as well, the front surface of the secondinsulating substrate of the pressure sensor element may be formed with aplurality of fit holes in each of which the second connection section ofeach of the metal terminal fitments is tightly fitted, wherein thesecond connection section of each of the metal terminal fitmentsincludes a fit portion fitted in each of the fit holes and a solderedportion arranged so as to extend along the front surface of the secondinsulating substrate and connected to the electrode section. Thus, apart of the second connection section of each of the metal terminalfitments is tightly fitted in the fit hole of the front surface of thesecond insulating substrate, so that the metal terminal fitment may bearranged on the second insulating substrate in a manner to upwardlyextend therefrom. Also, the soldered portion extending along the frontsurface of the second insulating substrate is connected to the electrodesection on the second insulating substrate by soldering, resulting inthe mechanical fixing and electrical connection being facilitated.

Further, in a preferred embodiment of the present invention, the firstconnection section of the metal terminal fitment is constructed so as tointerposedly support the circuit board in a direction of thicknessthereof. This facilitates fixing of the circuit board by means of thefirst connection section.

In the capacitance-type pressure sensor unit described above, thecircuit board is supported by only the metal terminal fitments.Alternatively, the circuit board may be supported by only the connectionconductors. In this instance, the circuit board is formed with aplurality of through-holes via which the connection conductors areinserted at a distal end thereof, resulting in being supported on thedistal end of each of the connection conductors. This permits assemblingof the pressure sensor unit without applying a pressure at an increasedlevel to the circuit board, unlike the prior art. In this instance, theelectrical connection means which include a plurality of metal terminalfitments each formed by subjecting a flexible metal plate to machiningare arranged, wherein the terminal fitments each are provided at one endthereof with a first connection section formed with through-holes viawhich the connection conductors are inserted at the distal end thereofand connected to the distal end by soldering and at the other endthereof with a second connection section which is fixed with respect tothe second insulating substrate of the pressure sensor element andconnected to each of the output electrodes by soldering. When thecircuit pattern (first circuit pattern) is formed on the front surfaceof the second insulating substrate of the pressure sensor element, thesecond connection section of each of the metal terminal fitments may beconnected to the electrode section contained in the first circuitpattern by soldering. Such metal terminal fitments permit the outputelectrodes on the second insulating substrate and the circuit pattern(second circuit pattern) on the circuit board to be connected to eachother. Alternatively, the electrode section of the first circuit patternand the second circuit pattern on the circuit board may be connected toeach other through the connection conductors of the connector. Theelectrical connection means are formed by machining of a metal plate, tothereby be reduced in manufacturing cost as compared with a flexibleprinted board, leading to a reduction in cost of the pressure sensorunit.

In a preferred embodiment of the present invention, the front surface ofthe second insulating substrate of the pressure sensor element is formedwith a plurality of fit holes in each of which the second connectionsection of each of the metal terminal fitments is tightly fitted,wherein the second connection section of each of the metal terminalfitments includes a fit portion fitted in each of the fit holes and asoldered portion arranged so as to extend along the front surface of thesecond insulating substrate and connected to the electrode section.Thus, the fit portion of the second connection section of the terminalfitment is tightly fitted in the fit hole of the second insulatingsubstrate, resulting in being raised and the soldered portion of thesecond connection section is connected to either the output electrode onthe second insulating substrate or the output electrode of the firstcircuit pattern by soldering, so that the terminal fitment may bemechanically fixed on the second insulating substrate with ease whilebeing electrically connected thereto.

In a preferred embodiment of the present invention, the metal terminalfitments are fixed on a single molded piece made of an insulating resinmaterial. Such a molded piece permits fixing of the metal terminalfitments and electrical connection thereof to be efficiently attained.In this instance, the metal terminal fitments are preferablyinsert-molded in the molded piece. This permits incorporation of theterminal fitments into a common molded piece to be readily accomplishedin a lump.

Thus, the capacitance-type pressure sensor unit of the present inventionis so constructed that the circuit board is supported by at least one ofthe connection conductors of the connector and the metal terminalfitments. Such construction permits assembling of the pressure sensorunit to be attained without applying a pressure at an increased level tothe circuit board, unlike the prior art. Also, the pressure sensorelement and the circuit patterns of the circuit boards are electricallyconnected to each other through the metal terminal fitments, so that theelectrical connection therebetween may be smoothly carried out even whenthe circuit board is kept suspended in the circuit component receivingchamber.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(A) to 1(C) show a first embodiment of a capacitance-typepressure sensor unit according to the present invention, wherein FIG.1(A) is a plan view of the capacitance-type pressure sensor unit, FIG.1(B) is a section view taken along line 1B—1B of FIG. 1(A) and FIG. 1(C)is a sectional view taken along line 1C—1C of FIG. 1(A);

FIG. 2(A) is a plan view showing a first insulating substrateincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A);

FIG. 2(B) is a sectional view taken along line 2B—2B of FIG. 2(A);

FIG. 2(C) is a sectional view of the first insulating substrate shown inFIG. 2(A);

FIG. 3(A) is a plan view showing a second insulating substrateincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A);

FIG. 3(B) is a sectional view taken along line 3B—3B of FIG. 3(A);

FIG. 3(C) is a sectional view taken along line 3C—3C of FIG. 3(A);

FIG. 3(D) is a right side elevation view of the second insulatingsubstrate shown in FIG. 3(A);

FIG. 4(A) is a bottom view showing a circuit board incorporated in thecapacitance-type pressure sensor unit shown in FIG. 1(A), from which acircuit pattern is omitted for the sake of brevity;

FIG. 4(B) is a sectional view taken along line 4B-4B of FIG. 4(A);

FIG. 5(A) is a front elevation view showing a metal terminal fitmentincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A);

FIG. 5(B) is a left side elevation view of the terminal fitment shown inFIG. 5(A);

FIG. 5(C) is a right side elevation view of the terminal fitment shownin FIG. 5(A);

FIG. 5(D) is a plan view of the terminal fitment shown in FIG. 5(A);

FIG. 6(A) is a front elevation view showing a ground terminal fitmentincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A);

FIG. 6(B) is a left side elevation view of the terminal fitment shown inFIG. 6(A);

FIG. 6(C) is a right side elevation view of the terminal fitment shownin FIG. 6(A);

FIG. 6(D) is a plan view of the terminal fitment shown in FIG. 6(A);

FIG. 7 is a vertical sectional view showing a second embodiment of acapacitance-type pressure sensor unit according to the presentinvention;

FIG. 8(A) is a plan view showing a circuit board support structure onwhich a circuit board is supported;

FIG. 8(B) is a front elevation view of the circuit board supportstructure shown in FIG. 8(A);

FIG. 8(C) is a right side elevation view of the circuit board supportstructure shown in FIG. 8(A);

FIG. 9 is a vertical sectional view showing a modification of thecapacitance-type pressure sensor unit shown in FIG. 7;

FIGS. 10(A) and 10(B) show a third embodiment of a capacitance-typepressure sensor unit according to the present invention, wherein FIG.10(A) is a vertical sectional view of the capacitance-type pressuresensor unit and FIG. 10(B) is a sectional end view taken along line10B—10B of FIG. 10(A);

FIG. 11(A) is a front elevation view showing a metal terminal fitmentincorporated in the capacitance-type pressure sensor unit shown in FIG.10(A);

FIG. 11(B) is a left side elevation view of the terminal fitment shownin FIG. 11(A);

FIG. 11(C) is a plan view of the terminal fitment shown in FIG. 11(A);

FIG. 12 is a perspective view showing another example of a metalterminal fitment incorporated in the capacitance-type pressure sensorunit shown in FIG. 10(A);

FIGS. 13(A) and 13(B) show a modification of the capacitance-typepressure sensor unit shown in FIGS. 10(A) and 10(B), wherein FIG. 13(A)is a vertical sectional view of the pressure sensor unit and FIG. 13(B)is a sectional end view taken along line 13B—13B of FIG. 13(A); and

FIG. 14 is a vertical sectional view showing a conventionalcapacitance-type pressure sensor unit which is to be improved by thepresent invention.

BEST MODE FOR CARRYING OUT INVENTION

Referring first to FIGS. 1(A) to 6(D), a first embodiment of acapacitance-type pressure sensor unit according to the present inventionis illustrated; wherein FIG. 1(A) is a plan view showing acapacitance-type pressure sensor unit of the illustrated embodiment,FIG. 1(B) is a sectional view taken along line 1B—1B of FIG. 1(A), FIG.1(C) is a sectional view taken along line 1C—1C of FIG. 1(A), FIG. 2(A)is a plan view showing a first insulating substrate incorporated in thecapacitance-type pressure sensor unit shown in FIG. 1(A), FIG. 2(B) is asectional view taken along line 2B—2B of FIG. 2(A), FIG. 2(C) is abottom view of the first insulating substrate shown in FIG. 2(A), FIG.3(A) is a plan view showing a second insulating substrate incorporatedin the capacitance-type pressure sensor unit shown in FIG. 1(A), FIG.3(B) is a sectional view taken along line 3B—3B of FIG. 3(A), FIG. 3(C)is a sectional view taken along line 3C—3C of FIG. 3(A), FIG. 3(D) is aright side elevation view of the second insulating substrate shown inFIG. 3(A), FIG. 4(A) is a bottom view showing a circuit boardincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A), from which a circuit pattern is omitted for the sake of brevity,FIG. 4(B) is a sectional view taken along line 4B—4B of FIG. 4(A), FIG.5(A) is a front elevation view showing a metal terminal fitmentincorporated in the capacitance-type pressure sensor unit shown in FIG.1(A), FIG. 5(B) is a left side elevation view of the terminal fitmentshown in FIG. 5(A), FIG. 5(C) is a right side elevation view of theterminal fitment shown in FIG. 5(A), FIG. 6(A) is a front elevation viewshowing a ground terminal fitment incorporated in the capacitance-typepressure sensor unit shown in FIG. 1(A), FIG. 6(B) is a left sideelevation view of the terminal fitment shown in FIG. 6(A), FIG. 6(C) isa right side elevation view of the terminal fitment shown in FIG. 6(A)and FIG. 6(D) is a plan view of the terminal fitment shown in FIG. 6(A).

The capacitance-type pressure sensor unit of the illustrated embodiment,as shown in FIGS. 1(A) to 1(C), generally includes a capacitance-typepressure sensor element 3, a circuit board 9, a receiving casing 13 anda connector 5.

The capacitance-type pressure sensor element 3, as shown in FIGS. 1(A)to 1(C), includes a first insulating substrate 1 made of an insulatingmaterial such as a ceramic material or the like. The first insulatingsubstrate 1 has a front surface formed thereon with a first capacitancedetecting electrode pattern (not shown) and a rear surface acting as apressure sensing material 1 a. The pressure sensor element 3 alsoincludes a second insulating substrate 2 made of an insulating materialsuch as a ceramic material or the like and fixed with respect to thefirst insulating substrate 1. The second insulating substrate 2 isprovided on a rear surface thereof with a second capacitance detectingelectrode pattern (not shown), which is arranged opposite to the firstcapacitance detecting electrode pattern while being spaced therefrom atan interval. The electrode patterns each may be constructed in such amanner as shown in Japanese Patent Application Laid-Open Publication No.94469/1996, Japanese Patent Application Laid-Open Publication No.90097/1998 (Japanese Patent Application No. 247395/1996) or the like.The first insulating substrate 1, as shown in FIGS. 2(A) to 2(C), isformed into a contour of a substantially circular shape in plan. Therear surface of the first insulating substrate 1 acting as the pressuresensing surface 1 a is recessed in the form of a circular shape of apredetermined radius, resulting in having a thickness sufficient topermit the first insulating substrate 1 to be deformed by a fluidpressure applied thereto. The capacitance-type pressure sensor unit ofthe illustrated embodiment also includes a second insulating substrate2, which has a side wall 2 b formed thereon with a flat section 2 d onwhich a plurality of output electrodes 2 c are arranged. In theillustrated embodiment, three such output electrodes 2 c are arranged.Also, the side wall 2 b of the second insulating substrate 2 is formedon a portion thereof opposite to the flat section 2 d with a recess(groove) 2 e in which the other end of a ground terminal fitmentdescribed hereinafter is received. The second insulating substrate 2 hasa front surface 2 a formed thereon with a heat diffusion restrainingrecess (groove) 2 f in a manner to extend in parallel to the flatsection 2 d while being spaced therefrom at a predetermined interval.Further, the front surface 2 a of the second insulating substrate 2 isformed thereon two or more recesses 2 g for positioning a connector bodydescribed hereinafter while orientating it in parallel with the flatsection 2 d. In the illustrated embodiment, two such recesses 2 g arearranged. The capacitance-type pressure sensor element 3 thusconstructed functions to detect a variation in pressure acting on thepressure sensing surface 1 a of the first insulating substrate 1depending on a variation in capacitance between the first capacitancedetecting electrode pattern and the second capacitance detectingelectrode pattern. Electrical connection between the output electrodes 2c and the first and second capacitance detecting electrode patterns maybe established as disclosed in FIGS. 1 and 3 of Japanese PatentApplication Laid-Open Publication No. 94469/1996. The output electrodes2 c may be arranged in a manner to be positioned on three wiringsconstituted of a conductive paste and arranged on a side surface of apressure sensor element shown in FIGS. 1 and 3 of Japanese PatentApplication Laid-Open Publication No. 94469/1996. The output electrodes2 c may be formed of a conductive paste such as a glass silver paint orthe like into a thick conductive film. Alternatively, the electrodes 2 cmay be made in the form of a thin conductive film by deposition or thelike. One of three such output electrodes 2 c is connected to the firstcapacitance detecting electrode pattern (counter electrode pattern) onthe first insulating substrate 1, another one of them is connected to amain electrode pattern and a reference electrode pattern each includedin the second capacitance detecting electrode pattern on the secondinsulating substrate 2.

The receiving casing 13 is made of metal and, as shown in FIGS. 1(B) and1(C), includes a casing body formed on one end thereof with an openingand including a bottom wall section 13 a provided on the other endthereof and a cylindrical peripheral wall section 13 b connected at oneend thereof to the bottom wall section 13 a. The bottom wall section 13a of the receiving casing 13 is provided with a fluid inlet port 14which permits a pressure measured fluid such as gas, liquid or the likeof which a pressure is to be measured to be introduced therethrough intothe capacitance-type pressure sensor unit. In the illustratedembodiment, the receiving casing 13 also includes a cylindrical section13 integrally provided on a central region of the bottom wall section 13a in a manner to surround the fluid inlet port 14 and a threaded section13 d arranged on an outer periphery of the cylindrical section 13 c. Thepressure sensor element 3 constituted by a combination of the firstinsulating substrate 1 and second insulating substrate 2 is arranged inthe peripheral wall section 13 b of the receiving casing 13 in such amanner that the pressure sensing surface 1 a of the first insulatingsubstrate 1 is rendered opposite to the bottom wall section 13 a of thereceiving casing 13. Between the pressure sensing surface 1 a of thefirst insulating substrate 1 and the bottom wall section 13 a of thereceiving casing 13 is defined a fluid chamber 15 into which thepressure measured fluid is introduced. Also, between the pressuresensing surface 1 a and the bottom wall section 13 a is arranged a sealmember 16 in a manner to be contacted with the pressure sensing surface1 a, the bottom wall section 13 a and the inner peripheral surface ofthe peripheral wall section 13 b to seal the fluid chamber 15. The sealmember 16 may be constituted by an O-ring.

The circuit board 9 includes a board member 9 a made of a glass-epoxyboard material of a one- or more-layer structure and a predeterminedcircuit pattern formed on each of both or upper and lower surfaces ofthe board member 9 a. More particularly, the board member 9 a is mountedon the lower surface thereof with an integrated circuit element 4 whichis one of a plurality of electrical circuit components constituting asignal processing circuit for processing an output of the pressuresensor element 3. Also, the board member 9 a of the circuit board 9 ismounted on the front surface thereof with electrical circuit components12 a and 12 b such as a capacitor or the like for eliminating noise orthe like which enters the circuit board 9 from an outer end section 8 bof each of connection conductors 8 of the connector 5 describedhereinafter. Further, the board member 9 a formed into a substantiallycircular shape, as shown in FIGS. 4(A) and 4(B), is provided on a sidewall section 9 b thereof defined on a side thereof positionallycorresponding to the flat section 2 d of the side wall section 2 b ofthe second insulating substrate 2 with a flat section 9 c. Also, theside wall section 9 b is formed on a portion thereof on a side thereofopposite to the flat section 9 c with a flat section 9 d. In addition,the board member 9 a is formed with a plurality of terminal fitmentconnection through-holes 9 e in a manner to be arranged in a row alongthe flat section 9 c. In addition, the board member 9 a is formed on aportion of a peripheral edge thereof extending in a directionperpendicular to the flat section 9 c with a plurality of connectionconductor connection through-holes 9 f in a manner to be arranged in arow in a direction perpendicular to a direction of arrangement of theterminal fitment connection through-holes 9 e. In the illustratedembodiment, three such terminal fitment connection through-holes 9 e andthree such connection conductor connection through-holes 9 f arearranged. Moreover, the board member 9 a is formed on a portion of theperipheral edge thereof positioned opposite to the flat section 9 c witha ground terminal fitment connection through-hole 9 g. The through-holes9 e to 9 g each are formed at an open end thereof positioned on a rearsurface of the board member 9 a with a soldering land so as to surroundthe open end. The circuit pattern for mounting the integrated circuitcomponent 4 and the like thereon is not shown in FIG. 4(A) for the sakeof brevity. The circuit board 9 thus constructed is so arranged that acomponent mounting surface thereof extend along the front surface 2 a ofthe second insulating substrate 2 of the pressure sensor element 3.

The connector 5 includes a connector body (connector housing) 6 made ofan insulating material such as a synthetic resin material or the likeand including a base 6 b formed therein with a circuit componentreceiving chamber 7 for receiving the circuit board 9 therein in amanner to be open on one surface (lower surface) of the base 6 b. Also,the connector 5 includes a plurality of the above-described connectionconductors (connector terminals) 8 fixed in the connector body 6 in sucha manner that one end thereof is projected into the circuit componentreceiving chamber 7 and electrically connected to the circuit pattern onthe circuit board 9 and the other end thereof is outwardly exposed. Inthe illustrated embodiment, the base 6 b of the connector 5 is providedon an outer periphery of a distal end thereof with two or moreprojections 6 d, which are fitted in the recesses 2 g of the frontsurface 2 a of the second insulating substrate 2, resulting in relativepositioning between the connector body 6 and the pressure sensor element3 being ensured. In the illustrated embodiment, two such projections 6 dare arranged. The connection conductors 8 each are so arranged that aninner end 8 a thereof is fittedly inserted into each of the connectionconductor connection through-holes 9 f of the circuit board 9 and thenconnected to the soldering land around the through-hole 9 f bysoldering, resulting in being electrically connected to the circuitpattern (not shown).

The circuit board 9 is arranged in the circuit component receivingchamber 7 in a substantially suspended manner while being mechanicallysupported by cooperation of the connection conductors 8, the base 6 b ofthe connector body 6, a plurality of metal terminal fitments 19 fixed onthe second insulating substrate 2 of the pressure sensor element 3 andacting as a circuit board support structure 18 as well, and a groundterminal fitment 22. In the illustrated embodiment, three such metalterminal fitments 19 are arranged. The circuit patterns on the circuitboard 9 and the output electrodes 2 c of the pressure sensor element 3are electrically connected to each other by means of three such metalterminal fitments 19.

The metal terminal fitments 19, as shown in FIGS. 1(A) and 5(A) to 5(D),each include a first section 19 c and a second section 19 d. The firstsection 19 c of the metal terminal fitment 19 has one end 19 c 1inserted through each of the terminal fitment connection through-holes 9e and connected to the soldering land formed around the through-hole 9 eby soldering. The first section 19 c also has the other end 19 c 2tightly fitted in a portion of a wall of the connector body 6 whichdefines the circuit component receiving chamber 7 and arranged oppositeto the circuit board 9. The second section 19 d has one end 19 d 1formed integrally with the first end 19 c and the other end 19 d 2connected to each of the output electrodes 2 c of the pressure sensorelement 3 by soldering. The second section 19 d is formed at a portionthereof between the one end 19 d 1 and the other end 19 d 2 into ameandering shape, resulting in exhibiting elasticity.

In electrical connection of the other end 19 d 2 of the second section19 d of the metal terminal fitment 19 to the output electrode 2 cprovided on the side wall section 2 b of the second insulating substrate2 of the pressure sensor element 3 by soldering, heat by the solderingis diffused to the second insulating substrate 2, leading to a failurein satisfactory soldering the other end 19 d 2 of the second section 19d to the output electrode 2 c. In view of such a disadvantage, in theillustrated embodiment, the second insulating substrate 2 is formedthereon with the heat diffusion restraining recess (groove) 2 f in amanner to extend in parallel to the flat section 2 d on which the outputelectrodes 2 c are arranged. The recess 2 f effectively restrains theheat diffusion described above, to thereby ensure satisfactory solderingof the other end 19 d 2 of the second section 19 d to the outputelectrode 2 c. Also, the second section 19 d of the metal terminalfitment 19 is provided at an intermediate portion thereof with apositioning projection 19 d 3 in a sideways manner which is abuttedagainst the front surface of the second insulating substrate 2 duringpositioning of the other end 19 d 2 of the second section 19 d withrespect to the second section 19 d.

The ground terminal fitment 22 is connected to the soldering land(ground electrode) arranged around the ground terminal fitmentconnection through-hole 9 g (FIG. 4) formed through the circuit patternon the circuit board 9. The ground terminal fitment 22 includes a firstsection 22 a and a second section 22 b. The first section 22 a has oneend 22 a 1 connected via the ground terminal fitment connectionthrough-hole 9 g of the circuit board 9 to the soldering land formedaround the rear-side opening of the through-hole 9 g by soldering andthe other end 22 a 2 tightly fitted in a portion of a wall of theconnector body 6 which surrounds the circuit component receiving chamber7 and is opposite to the circuit board 9, resulting in being fixed tothe connector body 6. Also, the second section 22 b has one end 22 b 1integrated with the first section 22 a and the other end 22 b 2 bentinto a hook-like shape and contacted with an inner surface of thereceiving casing 13 while exhibiting elasticity. The second section 22 bis curved at a portion between the one end 22 b 1 and the other end 22 b2, resulting in exhibiting elasticity. In the illustrated embodiment,the second section 22 b is so formed that the other end 22 b 2 extendsto the second insulating substrate 2 and is fitted in the recess 2 e ofthe side wall section 2 b of the second insulating substrate 2,resulting in being contacted with the inner surface of the receivingcasing 13.

More particularly, in the illustrated embodiment, the circuit board 9 issupported by cooperation of a plurality of the connection conductors 8of the connector 5, a plurality of the metal terminal fitments 19 andthe ground terminal fitment 22 while being kept suspended in the circuitcomponent receiving chamber 7.

The circuit board 9 is received in the circuit component receivingchamber 7 of the connector 5 and connected to the three metal terminalfitments 19 and ground terminal fitment 22 by soldering and then the end19 d 2 of each of the three metal terminal fitments 19 is connected toeach of the output electrodes 2 c of the pressure sensor element 3 bysoldering. Then, the base 6 b of the connector body 6 and the pressuresensor element 3 are inserted into the receiving casing 13 while keepingthe pressure sensor element 2 temporarily fixed to the end of theconnector 5. During the operation, an annular seal member 17 constitutedby an O-ring is interposedly arranged between a connector-side step 6 eannularly formed on an outer periphery of the base 6 b of the connectorbody 6 and a portion of an inner surface of the side wall section 13 bof the receiving casing 13 to provide waterproof sealing between theconnector-side step 6 e and a casing-side step 13 f formed on the innersurface of the receiving casing 13. Arrangement of the seal member orO-ring 17 therebetween while keeping it compressed effectively preventsleakage of fluid from the peripheral wall section 13 b of the receivingcasing 13 and the outer periphery of the base 6 b of the connector body6. Also, as described above, the seal member 16 is interposedly arrangedbetween the pressure sensor element 3 and the bottom wall section 13 aof the receiving casing 13. Then, an end 13 e of the receiving casing 13is subject to caulking (curling) toward the outer periphery of the base6 b of the connector body 6, resulting in assembling of the pressuresensor unit being completed.

Supporting of the circuit board 9 by cooperation of the three connectionterminals 8 of the connector 5, the three metal terminal fitments 19 andthe ground terminal fitment 22 while keeping it substantially suspendedin the circuit component receiving chamber 7 prevents application of apressure at an increased level to the circuit board 9 during thecaulking as encountered with the prior art. Also, in the illustratedembodiment, the three metal terminal fitments 19 and ground terminalfitment 22 are so constructed that the second sections 19 d and 22 bexhibit elasticity. The thus-exhibited elasticity permits the secondsections to absorb a variation in dimensions during the caulking, tothereby prevent application of undue force to the soldered portionsduring the assembling. Also, in the illustrated embodiment, the metalterminal fitments 19 function as both the electrical connection meansfor electrically connecting the circuit board 9 and the outputelectrodes 2 c of the second insulating substrate 2 to each other andthe mechanical support means for supporting the circuit board 9, so thatthe pressure sensor unit may be simplified in structure and reduced inmanufacturing cost.

Also, use of the three metal terminal fitments 19 for electricalconnection between the pressure sensor element 3 and the circuitpatterns on the circuit board 9 permits the pressure sensor element 3and the circuit patterns on the circuit board 9 to be satisfactorilyelectrically connected to each other even when the circuit board 9 isarranged in the circuit component receiving chamber 7 while being keptsuspended therein. In particular, in the illustrated embodiment, themetal terminal fitments 19 each permit the one end 19 c 1 of the firstsection 19 c to electrically connect the fitment 19 to the electrodeincorporated in each of the circuit patterns on the circuit board 9 bysoldering and the other end 19 c 2 to fix it to the portion of the wallof the connector body 6 which surrounds the circuit component receivingchamber 7 and is opposite to the circuit board 9. Also, the secondsection 19 d may be integrated at the one end 19 d 1 thereof with thefirst section 19 c and connected at the other end 19 d 2 thereof to theoutput electrode 2 c of the pressure sensor element 3 by soldering.

In addition, the ground electrode of the circuit pattern on the circuitboard 9 and the receiving casing are electrically connected to eachother with ease by means of the ground terminal fitment 22 made ofmetal. In particular, in the illustrated embodiment, the ground terminalfitment 22 permits the one end 22 a 1 of the first section 22 a to beconnected to the electrode incorporated in the circuit pattern on thecircuit board 9 and the other end 22 a 2 to be fixed to the portion ofthe wall of the connector body 6 which surrounds the circuit componentreceiving chamber 7 and is opposite to the circuit board 9. Further, thesecond section 22 b may be integrated at the one end 22 b 1 thereof withthe first section 22 a and contacted at the other end 22 b 2 with theinner surface of the receiving casing 3.

Further, the first insulating substrate 1 of the pressure sensor element3 is formed into a contour in plan of a substantially circular shape.Such configuration of the first insulating substrate 1 facilitatessealing between the first insulating substrate 1 and the peripheral wallsection 13 b of the receiving casing 14 by means of the seal member 16in the fluid chamber 15 defined between the pressure sensing surface 1 aof the first insulating substrate 1 and the bottom wall section 13 a ofthe receiving casing 13. Also, when the side wall section 2 b of thesecond insulating substrate 2 of the pressure sensor element 3 is formedwith the flat section 2 d on which the output electrodes 2 c arearranged, arrangement of the output electrodes 2 c may be facilitatedusing the flat section 2 d. Moreover, when the side wall section 2 b ofthe second insulating substrate 2 is formed on the portion thereofopposite to the flat section 2 d with the recess 2 e in which the otherend 22 b 2 of the ground terminal fitment 22 is fitted, the other end 22b 2 of the ground terminal fitment 22 is permitted to be contacted withthe inner surface of the receiving casing 13 through the recess 2 e, sothat the other end 22 b 2 of the ground terminal fitment 22 may beformed into any desired length without adversely affecting the pressuresensor unit.

Furthermore, the connector body 6 is integrally provided on the endthereof with the projections 6 d and correspondingly the secondinsulating substrate 2 of the pressure sensor element 3 is formed on thefront surface thereof with the recesses 2 g in which the projections 6 dare fitted, resulting in relative positioning between the connector body6 and the second insulating substrate 2 of the pressure sensor element 3being ensured.

In the illustrated embodiment, the integrated circuit element 4 isarranged on the rear surface of the circuit board 9. Alternatively, itmay be provided on the front surface of the circuit board 9.

Referring now to FIGS. 7 and 8(A) to 8(C), a second embodiment of acapacitance-type pressure sensor unit according to the present inventionis illustrated, wherein FIG. 7 is a vertical sectional view of acapacitance-type pressure sensor unit of the illustrated embodiment,FIG. 8(A) is a plan view showing a circuit board support structure 18 onwhich a circuit board 9 is supported, FIG. 8(B) is a front elevationview of the circuit board support structure shown in FIG. 8(A), and FIG.8(C) is a right side elevation view of the circuit board supportstructure shown in FIG. 8(A). Reference characters in FIGS. 7 to 8(C)like those in FIG. 14 designate corresponding parts.

The capacitance-type pressure sensor unit of the illustrated embodimentis so constructed that a second insulating substrate 2 is mounted on afront surface 2 a thereof with at least one electric circuit component 4such as an integrated circuit element or the like for processing anoutput of a pressure sensor element 3 while being electrically connectedto a first circuit pattern (not shown) on the front surface 2 a of thesecond insulating substrate 2.

The circuit board 9 is supported by the circuit board support structure18 constituted of four terminal fitments 19 made of metal and fixed onthe second insulating substrate 2 of the pressure sensor element 3. Themetal terminal fitments 19 not only function to constitute the circuitboard support structure 18 for supporting the circuit board 9 but act aselectrical connection means like the electrical connection means 11shown in FIG. 14.

The metal terminal fitments 19 each may be formed by subjecting a metalplate to machining such as pressing, bending or the like. The metalterminal fitment 19 is provided at one end thereof with a firstconnection section 19 a fixed to the circuit board 9 and connected to anelectrode section incorporated in a second circuit pattern (now shown)on the circuit board 9 by soldering as required and at the other endthereof with a second connection section 19 b fixed to the secondinsulating substrate 2 of the pressure sensor element 3 and connected toan electrode section incorporated in a first circuit pattern (not shown)formed on the front surface of the second insulating substrate 2 bysoldering. The first connection section 19 a provided at a distal end ofthe metal terminal fitment 19 is constructed so as to interposedlysupport the circuit board 9 in a direction of thickness of the circuitboard 9. The first connection section 19 a for interposedly supportingthe circuit board 9 is connected to the electrode section incorporatedin the second circuit pattern (now shown) on the circuit board 9. Thefirst connection section 19 a for interposedly supporting the circuitboard 9 may be constructed in any desired manner. In the illustratedembodiment, the first connection section 19 a is constituted of a pairof holding elements arranged opposite to each other. Such constructionof the first connection section 19 a facilitates holding of the circuitboard 9 by the first connection section 9. In order to reinforce theholding, an adhesive may be applied in a manner to extend over the firstconnection section 19 a and circuit board 9.

The second connection section 19 b of the metal terminal fitment 19includes a fit portion 19 b 1 fitted in each of fit holes (not shown) ofthe second insulating substrate 2 of the pressure sensor element 3 and asoldered portion 19 b 2 arranged so as to extend along the front surfaceof the second insulating substrate 2, resulting in being fixed to thesecond insulating substrate 2 and connected to the electrode sectionincorporated in the first circuit pattern by soldering. For thispurpose, the metal terminal fitment 19 is arranged on the secondinsulating substrate 2 so as to upwardly extend therefrom by tightlyfitting the fit portion 19 b 1 of the second connection section 19 inthe fit hole of the front surface of the second insulating substrate 2of the pressure sensor element 3. Then, the metal terminal fitment 19extends at the soldered portion 19 b 2 thereof along the front surfaceof the second insulating substrate 2, resulting in being connected tothe electrode section (not shown) of the first circuit pattern bysoldering. In fitting of the fit portion 19 b 1 of the second connectionsection 19 b in the fit hole of the second insulating substrate 2, anadhesive may be previously charged in the fit hole, to thereby enhancefixing of the metal terminal fitment 19 to the second insulatingsubstrate 2.

The second circuit pattern (not shown) on the circuit board 9 and aninner end 8 a of each of a plurality of connection conductors 8 of aconnector 5 are electrically connected to each other through a lead wire20 of a suitable length during assembling of the pressure sensor unit.Such electrical connection between the second circuit pattern on thecircuit board 9 and the connection conductors 8 of the connector 9through the lead wires 20 of a required length permits electricalconnection between the circuit board 9 supported on the pressure sensorelement 3 through the metal terminal fitments 18 and the connectionconductors 8 incorporated in the connector 5 to be facilitated bydefining an interval of a required size between the circuit board 9 andthe connection conductors 8 of the connector 5 using the lead wires 10of a required length.

An engagement between a connector body 6 and an end edge 13 e of areceiving casing 13 by caulking is sealed by means of an external seal21 formed by application of an adhesive or the like.

Such supporting of the circuit board 9 by the metal terminal fitments 19fixed to the second insulating substrate 2 of the pressure sensorelement 3 permits assembling of the pressure sensor unit to be attainedwhile keeping a pressure at an increased level from being applied to thecircuit board, unlike the prior art. Also, the metal terminal fitments19 act also as the electrical connection means for electricallyconnecting the circuit board 9 and the first circuit pattern on thefront surface of the second insulating substrate 2 to each other, sothat the pressure sensor unit may be simplified in structure and reducedin manufacturing cost.

In the illustrated embodiment, the first connection section 19 a of eachof the metal terminal fitments 19 is constructed so as to interposedlysupport the circuit board 9, however, the first connection section 19 ais not limited to such construction. For example, the illustratedembodiment may be constructed in such a manner that the circuit board 9is formed with through-holes for mounting and the first connectionsection 19 a includes a fit portion fitted in each of the mountingthrough-holes and a support portion for the circuit board 9. Also, inthe illustrated embodiment, the circuit board support structure 18 isconstituted of the four metal terminal fitments 19. However, the numberof metal terminal fitments 19 is merely set so as to permit them tosupport the circuit board 9. Thus, three or more such metal terminalfitments 19 are required.

Referring now to FIG. 9, a modification of the capacitance-type pressuresensor unit described above with reference to FIG. 7 is illustrated. Acapacitance-type pressure sensor unit of the modification includes atleast one electric circuit component 4 such as an integrated circuit orthe like which is electrically connected to a circuit pattern (notshown) arranged on a rear surface of a circuit board 9 to carry outprocessing of an output of a pressure sensor element 3. Thus, in themodification, the electric circuit component 4 is not arranged on afront surface 2 a of a second insulating substrate 2, unlike theembodiment shown in FIG. 7. Instead, the front surface 2 a of the secondinsulating substrate 2 is formed thereon with output electrodes of thepressure sensor element 3 and metal terminal fitments 19 are arranged soas to electrically connect the output electrodes and the circuitpatterns on the circuit board 9 to each other therethrough. Theremaining part of the modification may be constructed in substantiallythe same manner as the embodiment of FIG. 7.

Referring now to FIGS. 10(A) and 10(B) and FIGS. 11(A) to 11(C), a thirdembodiment of a capacitance-type pressure sensor unit is illustrated,wherein FIG. 10(A) is a vertical sectional view of a capacitance-typepressure sensor unit of the third embodiment, FIG. 10(B) is a sectionalend view taken along line 10B-10B of FIG. 10(A), FIG. 11(A) is a frontelevation view showing a metal terminal fitment incorporated in thecapacitance-type pressure sensor unit shown in FIG. 10(A), FIG. 11(B) isa left side elevation view of the terminal fitment shown in FIG. 11(A)and FIG. 11(C) is a plan view of the terminal fitment shown in FIG.11(A). Reference characters in FIGS. 10(A) to 11(C) like those in FIG. 4designate corresponding parts.

The capacitance-type pressure sensor unit of the third embodiment is soconstructed that at least one electric circuit component 4 such as anintegrated circuit or the like which is electrically connected to afirst circuit pattern (not shown) arranged on a front surface 2 a of asecond insulating substrate 2 to carry out processing of an output of apressure sensor element 3 is mounted on the front surface 2 a of thesecond insulating substrate 2 by soldering.

A connector 5 includes a plurality of connection conductors 8. In theillustrated embodiment, the connector 5 includes three such connectionconductors or an input terminal, an output terminal and a groundterminal. The connection conductors 8 are arranged in a row in adirection normal to the sheet of FIG. 10(A) and in a row in a verticaldirection in FIG. 10(B).

A circuit board 9 is formed with a plurality of through-holes 9 h andthe connection conductors 8 of the connector 5 each are formed with aninwardly-directed end 8 a, which is inserted through each of thethrough-holes 9 h. The through-holes 9 h each are provided therein witha through-hole conductor electrically connected to a second circuitpattern. The through-hole conductor is formed into a cylindrical shapeor formed at a central portion thereof with a through-hole. The circuitboard 9 is formed on a rear surface thereof with soldering lands eachelectrically connected to each of the through-hole conductors. Theconnection conductors 8 inserted through the through-holes 9 h each areconnected at the end thereof to each of the lands by soldering, so thatthe circuit board 9 is supported by the distal end or inwardly-directedend 8 a of each of the connection conductors. In order to facilitatepositioning of the circuit board 9, the distal end or inwardly-directedend 8 a may be formed with a step against which a front surface of thecircuit board 9 is abutted.

Electrical connection means 11 are constituted of a plurality of metalterminal fitments 19 each made by subjecting a flexible metal plate tomachining such as pressing, bending or the like. In the illustratedembodiment, the electrical connection means 11 are constituted by threesuch metal terminal fitments 19. The metal terminal fitments 19 arearranged in a row in a direction normal to the sheet of FIG. 10(A) incorrespondence to arrangement of the connection conductors 8.

The metal terminal fitments 19, as shown in FIG. 11(C), each areprovided at one end thereof with a first connection section 19 a, whichis formed with a through-hole 23 through which the distal end orinwardly-directed end 8 a of the connection conductor 8 is inserted andconnected to the inwardly-directed end 8 a of the connection conductor 8by soldering. Also, the metal terminal fitment 19 is provided at theother end thereof with a second connection section 19 b fixed to thesecond insulating substrate 2 of the pressure sensor element 3 andconnected to an electrode section incorporated in a first circuitpattern (not shown) on the second insulating substrate 2 by soldering.The second connection section 19 b includes a fit portion 19 b 1 fittedin a fit hole provided in the second insulating substrate 2 as describedhereinafter and a soldered portion 19 b 2 arranged so as to extend alongthe front surface 2 a of the second insulating substrate 2 and connectedto the electrode section of the first circuit pattern by soldering. Themetal terminal fitments 19 thus constructed permit the electrode sectionof the first circuit pattern on the second insulating substrate 2 andthe second circuit pattern on the circuit board 9 to be connected toeach other through the connection conductors 8 of the connector 5.

In this instance, the construction that the terminal fitments 19 eachare connected through the connection conductor 8 of the connector 5 tothe second circuit pattern on the circuit board 9 does not adverselyaffect the pressure sensor unit, because the electric circuit componentmounted on the second circuit pattern on the circuit board 9 isconstituted of a noise removing component such as a noise removingcapacitor or the like for removing noise intruding from the outsidethrough the connection conductors 8 into the circuit board and connectedbetween one connection conductor 8 for grounding and two connectionconductors 8 for signal outputting and inputting.

The second insulating substrate 2 of the pressure sensor element 3 isformed on the front surface thereof with a plurality of fit holes (notshown) in each of which the fit portion 19 b 1 of the second connectionsection 19 b of each of the metal terminal fitments 19 is tightlyfitted. The metal terminal fitments 19 each are constructed in such amanner that the fit portion 19 b 1 of the second connection section 19 bis tightly fitted in the corresponding fit hole of the second insulatingsubstrate 2 and the soldered portion 19 b 2 of the second connectionsection 19 b is arranged along the front surface 2 a of the secondinsulating substrate 2 and connected to the corresponding electrodesection of the first circuit pattern on the front surface 2 a of thesecond insulating substrate 2 by soldering. This results in the metalterminal fitments 19 being arranged on the second insulating substrate 2in a manner to upwardly extend therefrom or be raised. The fit holeseach may be previously charged therein with an adhesive, resulting infixing of the metal terminal fitment with respect to the secondinsulating substrate 2 being enhanced.

An engagement between a connector body 6 and an end edge 13 e of areceiving casing 13 by caulking is sealed by means of an external seal21 formed by application of an adhesive or the like.

Such supporting of the circuit board 9 on the distal end of each of theconnection conductors 8 of the connector 5 permits assembling of thepressure sensor unit while preventing application of a pressure at anincreased level to the circuit board 9 encountered with the prior art.

Also, the second insulating substrate 2 of the pressure sensor element 3is formed on the front surface thereof with a plurality of fit holes ineach of which the fit portion 19 b 1 of the second connection section 19b of each of the metal terminal fitments 19 is tightly fitted, so thatthe fit portion 19 b 1 of the second connection section 19 b of each ofthe terminal fitments 19 is tightly fitted in each of the fit holes,resulting in the terminal fitment being raised. Also, the solderedportion 19 b 2 of the second connection section 19 b is connected to theelectrode section of the first circuit pattern on the front surface 2 aof the second insulating substrate 2 by soldering. This permits theterminal fitment 19 to be readily mechanically fixed to the secondinsulating substrate 2 while being electrically connected thereto.

Also, flexibility of the metal terminal fitments 19 permits insertion ofeach of the connection conductors 8 through the through-hole 23 of thefirst connection section 19 a of each of the metal terminal fitments 19for bending of the metal terminal fitment 19 and soldering of theconnection conductor 8 to the metal terminal fitment 19 while keepinginsertion of the connection conductor 8 via the through-hole 23externally observed, in the state that the metal terminal fitments 19are kept supported on the pressure sensor element 3 and the circuitboard 9 is kept supported on the connection conductors 8 of theconnector 5. This facilitates assembling of the pressure sensor unit.

Referring now to FIG. 12, a modification of the metal terminal fitments19 incorporated in the third embodiment of the capacitance-type pressuresensor unit described above is illustrated.

In the modification, a plurality of metal terminal fitments 19 are fixedon a single molded piece 25 made of an insulating resin material,resulting in being constructed into a terminal fitment unit 26. In themodification, three such terminal fitments 19 are arranged. Moreparticularly, the metal terminal fitments 19 are insert-molded in thecommon molded piece 25, resulting in being formed into the terminalfitment unit 26.

In the terminal fitment unit 26, the metal terminal fitments 19 eachinclude a first connection section 19 a constructed in substantially thesame manner as that shown in FIG. 11 and a second connection section 19b formed in a plate-like manner and bent in a direction parallel to alower surface of the molded piece so as to facilitate surface mounting.

In the terminal fitment unit 26 thus constructed, the second connectionsections 19 b each are mounted on each of electrode sectionsincorporated in a first circuit pattern on a front surface of a secondinsulating substrate 2 of a pressure sensor element 3 for connection bysoldering.

The terminal fitment unit 26 permits fixing of the metal terminalfitments 19 and electrical connection thereof to be efficiently carriedout. Also, insert-molding of the metal terminal fitments in the moldedpiece 25 permits incorporation of the terminal fitments in the commonmolded piece 25 to be attained in a lump.

Referring now to FIGS. 13(A) and 13(B), a modification of thecapacitance-type pressure sensor unit shown in FIG. 10 is illustrated,wherein FIG. 13(A) is a vertical sectional view of a pressure sensorunit of the modification and FIG. 13(B) is a sectional end view takenalong line 13B—13B of FIG. 13(A).

The capacitance-type pressure sensor unit of the modification is soconstructed that at least one electric circuit component 4 such as anintegrated circuit or the like for processing an output of a pressuresensor element 3 is electrically connected to a circuit pattern (notshown) formed on a rear surface of a circuit board 9 by soldering. Thus,the electric circuit component 4 is not arranged on a front surface 2 aof a second insulating substrate 2, unlike the pressure sensor unit ofFIG. 10. The front surface 2 a of the second insulating substrate 2 isformed thereon with output electrodes for the pressure sensor element 3and metal terminal fitments 19 are arranged so as to electricallyconnect the output electrodes and the circuit patterns on the circuitboard 9 to each other. Also, connection conductors 8 are arranged so asto be electrically connected to the circuit pattern on the circuit board9. The remaining part of the modification may be constructed insubstantially the same manner as the pressure sensor unit shown in FIG.10.

INDUSTRIAL APPLICABILITY

The capacitance-type pressure sensor unit according to the presentinvention is so constructed that the circuit board is supported on atleast one of a plurality of the connection conductors and a plurality ofmetal terminal fitments. This permits assembling of the pressure sensorunit to be carried out without applying a pressure at an increased levelto the circuit board. Also, the pressure sensor element and the circuitpatterns on the circuit board are electrically connected to each otherthrough a plurality of the metal terminal fitments, so that electricalconnection between the pressure sensor and the circuit patterns on thecircuit board may be satisfactorily attained even when the circuit boardis kept suspended in the circuit component receiving chamber.

What is claimed is:
 1. A capacitance-type pressure sensor unitcomprising: a capacitance-type pressure sensor element including a firstinsulating substrate which is made of an insulating material and has afront surface provided thereon with a first capacitance detectingelectrode pattern and a rear surface constituting a pressure sensingsurface and a second insulating substrate which is made of an insulatingmaterial and fixed with respect to said first insulating substrate andhas a rear surface provided thereon with a second capacitance detectingelectrode pattern in a manner to be opposite to said first capacitancedetecting electrode pattern while being spaced at an interval therefrom;a receiving casing made of metal and including a cylindrical casing bodyprovided at one end thereof with an opening and at the other end thereofwith a bottom wall section, said bottom wall section being provided witha fluid inlet port through which a pressure measured fluid is introducedinto said receiving casing; a circuit board including a board memberprovided thereon with circuit patterns and mounted thereon with at leasta part of a plurality of electric circuit components constituting asignal processing circuit for processing an output of said pressuresensor element; and a connector including a connector body which is madeof an insulating material and includes a base formed on one surfacethereof with an opening and provided therein with a circuit componentreceiving chamber for receiving said circuit board therein in a mannerto communicate with said opening of said connector body; said connectoralso including a plurality of connection conductors fixed in saidconnector body and each having one end extending into said circuitcomponent receiving chamber and electrically connected to each of saidcircuit patterns on said circuit board and an other end externallyexposed; said circuit board having a component mounting surface arrangedso as to extend along a front surface of said second insulatingsubstrate of said pressure sensor element; said pressure sensor elementbeing received in said casing body of said receiving casing whilekeeping said pressure sensing surface facing said bottom wall section ofsaid casing body; said connector body being received in said casing bodyof said receiving casing in such a manner that said base of saidconnector body is positioned on a side of said opening of said receivingcasing rather than on a side of said pressure sensor element; saidreceiving casing being securely mounted at an end thereof positioned ona side of said opening of said connector body on said base of saidconnector body by caulking; said pressure sensor element and saidcircuit patterns on said circuit board being electrically connected toeach other through a plurality of metal terminal fitments; said circuitboard being supported by at least one of said connection conductors ofsaid connector and said metal terminal fitments.
 2. A capacitance-typepressure sensor unit comprising: a capacitance-type pressure sensorelement including a first insulating substrate which is made of aninsulating material and has a front surface provided thereon with afirst capacitance detecting electrode pattern and a rear surfaceconstituting a pressure sensing surface and a second insulatingsubstrate which is made of an insulating material and fixed with respectto said first insulating substrate and has a rear surface providedthereon with a second capacitance detecting electrode pattern in amanner to be opposite to said first capacitance detecting electrodepattern while being spaced at an interval therefrom; a receiving casingmade of metal and including a cylindrical casing body provided at oneend thereof with an opening and at the other end thereof with a bottomwall section, said bottom wall section being provided with a fluid inletport through which a pressure measured fluid is introduced into saidreceiving casing; a circuit board including a board member providedthereon with circuit patterns and mounted thereon with at least a partof a plurality of electric circuit components constituting a signalprocessing circuit for processing an output of said pressure sensorelement; and a connector including a connector body which is made of aninsulating material and includes a base formed on one surface thereofwith an opening and provided therein with a circuit component receivingchamber for receiving said circuit board therein in a manner tocommunicate with said opening of said base; said connector alsoincluding a plurality of connection conductors fixed in said connectorbody and each having one end extending into said circuit componentreceiving chamber and electrically connected to each of said circuitpatterns on said circuit board and the other end externally exposed;said circuit board having a component mounting surface arranged so as toextend along a front surface of said second insulating substrate of saidpressure sensor element; said pressure sensor element being received insaid casing body of said receiving casing while keeping said pressuresensing surface facing said bottom wall section of said casing body;said connector body being received in said casing body of said receivingcasing in such a manner that said base of said connector body ispositioned on a side of said opening of said receiving casing ratherthan on a side of said pressure sensor element; said receiving casingbeing securely mounted at an end thereof positioned on a side of saidopening of said connector body on said base of said connector body bycaulking; said pressure sensor element including a plurality of outputelectrodes electrically connected to said circuit patterns on saidcircuit board by means of a plurality of metal terminal fitments; saidcircuit board being supported by at least said connection conductors ofsaid connector and said metal terminal fitments.
 3. A capacitance-typepressure sensor unit as defined in claim 1, wherein said circuitpatterns include a ground electrode connected to said receiving casing;said ground electrode and said receiving casing being electricallyconnected to each other through a ground terminal fitment made of metal;said ground terminal fitment being arranged so as to support saidcircuit board.
 4. A capacitance-type pressure sensor unit comprising: acapacitance-type pressure sensor element including a first insulatingsubstrate which is made of an insulating material and has a frontsurface provided thereon with a first capacitance detecting electrodepattern and a rear surface constituting a pressure sensing surface and asecond insulating substrate which is made of an insulating material andfixed with respect to said first insulating substrate and has a rearsurface provided thereon with a second capacitance detecting electrodepattern in a manner to be opposite to said first capacitance detectingelectrode pattern while being spaced at an interval therefrom; saidcapacitance-type pressure sensor unit detecting a variation in pressureacting on said pressure sensing surface of said first insulatingsubstrate depending on a variation in capacitance between said firstcapacitance detecting electrode pattern and said second capacitancedetecting electrode pattern; a receiving casing made of metal andincluding a cylindrical casing body provided at one end thereof with anopening and at the other end thereof with a bottom wall section, saidbottom wall section being provided with a fluid inlet port through whicha pressure measured fluid is introduced into said receiving casing; acircuit board including a board member provided thereon with circuitpatterns and mounted thereon with at least a part of a plurality ofelectric circuit components constituting a signal processing circuit forprocessing an output of said pressure sensor element; and a connectorincluding a connector body which is made of an insulating material andincludes a base formed on one surface thereof with an opening andprovided therein with a circuit component receiving chamber forreceiving said circuit board therein in a manner to communicate withsaid opening of said connector body; said connector also including aplurality of connection conductors fixed in said connector body and eachhaving one end extending into said circuit component receiving chamberand electrically connected to each of said circuit patterns on saidcircuit board and the other end externally exposed; said circuit boardhaving a component mounting surface arranged so as to extend along afront surface of said second insulating substrate of said pressuresensor element; said pressure sensor element being received in saidcasing body of said receiving casing so that a fluid chamber which fluidintroduced through said fluid inlet port enters may be defined betweensaid pressure sensing surface and said bottom wall section of saidreceiving casing; said connector body being received in said casing bodyof said receiving casing in such a manner that said base of saidconnector body is kept contacted at an end thereof on a side of saidopening of said base with a front surface of said second insulatingsubstrate of said pressure sensor element; said receiving casing beingsecurely mounted at an end thereof positioned on a side of said openingof said connector body on said base of said connector body by caulking;said pressure sensor element and said circuit patterns on said circuitboard being electrically connected to each other through a plurality ofmetal terminal fitments; said circuit patterns including a groundelectrode connected to said receiving casing; said ground electrode andreceiving casing being electrically connected to each other through aground terminal fitment made of metal; said circuit board beingsupported by said connection conductors of said connector, said metalterminal fitments and said ground terminal fitment.
 5. Acapacitance-type pressure sensor unit as defined in claim 3 or 4,wherein said metal terminal fitments each include a first section havingone end connected to the electrode included in said circuit patterns ofsaid circuit board by soldering and the other end fixed to a portion ofa wall of said connector body which surrounds said circuit componentreceiving chamber and is opposite to said circuit board, as well as asecond section having one end formed integrally with said first sectionand the other end connected to each of output electrodes of saidpressure sensor element by soldering; said second section being formedat a portion thereof between said one end thereof and said the other endthereof into a shape which permits said second section to exhibitelasticity.
 6. A capacitance-type pressure sensor unit as defined inclaim 3 or 4, wherein said ground terminal fitment includes a firstsection having one end connected to the electrode included in saidcircuit patterns of said circuit board by soldering and the other endfixed to a portion of a wall of said connector body which surrounds saidcircuit component receiving chamber and is opposite to said circuitboard, as well as a second section having one end formed integrally withsaid first section and the other end contacted with an inner surface ofsaid receiving casing; said second section being formed at a portionthereof between said one end thereof and said the other end thereof intoa shape which permits said second section to exhibit elasticity.
 7. Acapacitance-type pressure sensor unit as defined in claim 3 or 4,wherein said first insulating substrate of said pressure sensor elementis formed into a contour of a substantially circular shape in plan; saidsecond insulating substrate of said pressure sensor element is formed ona side wall section thereof with a flat section on which a plurality ofoutput electrodes are arranged; and said second insulating substrate ofsaid pressure sensor element is formed at a portion of said side wallsection thereof opposite to said flat section with a recess in whichsaid the other end of said ground terminal fitment is fitted.
 8. Acapacitance-type pressure sensor unit as defined in claim 2 or 4,wherein said casing body of said receiving casing is formed on an innersurface thereof with an annular casing-side step; and said base of saidconnector body is formed on an outer periphery thereof with an annularconnector-side step; said annular casing-side step and connector-sidestep having a waterproof O-ring arranged therebetween while keeping saidO-ring compressed.
 9. A capacitance-type pressure sensor unit as definedin claim 4, wherein said end of said connector body is integrallyprovided with two or more projections; and said front surface of saidsecond insulating substrate is formed with two or more recesses in whichsaid projections are fitted.
 10. A capacitance-type pressure sensor unitcomprising: a pressure sensor element including a first insulatingsubstrate having a front surface provided thereon with an electrode anda rear surface acting as a pressure sensing surface and a secondinsulating substrate which has a rear surface provided thereon with anelectrode in a manner to be opposite to said electrode on said firstinsulating substrate while being spaced at a predetermined intervaltherefrom and is combined with said first insulating substrate; aplurality of output electrodes formed on one of a front surface of saidsecond insulating substrate and a side surface thereof and electricallyconnected to said electrodes; at least one electric circuit componentfor processing an output of said pressure sensor element; a connectorincluding a connector body which is made of an insulating resin materialand includes a base having an end surface contacted with said frontsurface of said second insulating substrate of said pressure sensorelement and provided therein with a circuit component receiving chamberfor receiving said electric circuit component therein; said connectoralso including a plurality of connection conductors supported in saidconnector body and each having one end positioned in said circuitcomponent receiving chamber and an other end externally exposed; acircuit board arranged in said circuit component receiving chamber whilebeing kept spaced from said front surface of said second insulatingsubstrate and including circuit patterns electrically connected to saidoutput electrodes and connection conductors; electrical connection meansfor electrically connecting said circuit board and output electrodes toeach other; and a receiving casing made of metal and including a bottomwall section formed with-a fluid inlet port for introducing pressuremeasured fluid therethrough and a peripheral wall section connected atone end thereof to said bottom wall section; said receiving casingreceiving said pressure sensor element and at least a part of said baseof said connector body therein so that a fluid chamber which saidpressure measured fluid enters may be defined between said pressuresensing surface of said pressure sensor element and said bottom wallsection; said circuit board being supported on a circuit board supportstructure fixed on said second insulating substrate of said pressuresensor element; said circuit board support structure acting also as saidelectrical connection means.
 11. A capacitance-type pressure sensor unitas defined in claim 10, wherein said circuit patterns of said circuitboard and said connection conductors are electrically connected to eachother through lead wires.
 12. A capacitance-type pressure sensor unit asdefined in claim 10 or 11, wherein said circuit board support structureis constituted by three or more metal terminal fitments each formed bysubjecting a metal plate to machining; said terminal fitments each beingprovided at one end thereof with a first connection section which isfixed on said circuit board and connected to an electrode sectionincluded in said circuit patterns by soldering as required and at theother end thereof with a second connection section which is fixed withrespect to said second insulating substrate of said pressure sensorelement and connected to each of said output electrodes by soldering.13. A capacitance-type pressure sensor unit as defined in claim 12,wherein said front surface of said second insulating substrate of saidpressure sensor element is formed with a plurality of fit holes in eachof which said second connection section of each of said metal terminalfitments is tightly fitted; said second connection section of each ofsaid metal terminal fitments including a fit portion fitted in each ofsaid fit holes and a soldered portion arranged so as to extend alongsaid front surface of said second insulating substrate and connected tosaid electrode section.
 14. A capacitance-type pressure sensor unit asdefined in claim 12 or 13, wherein said first connection section of saidmetal terminal fitment is constructed so as to interposedly support saidcircuit board in a direction of thickness thereof.
 15. Acapacitance-type pressure sensor unit comprising: a pressure sensorelement including a first insulating substrate having a front surfaceprovided thereon with an electrode and a rear surface acting as apressure sensing surface and a second insulating substrate which has arear surface provided thereon with an electrode in a manner to beopposite to said electrode on said first insulating substrate whilebeing spaced at a predetermined interval therefrom and is combined withsaid first insulating substrate; a first circuit pattern formed on afront surface of said second insulating substrate and electricallyconnected to said electrodes; at least one electric circuit componentarranged on said front surface of said second insulating substrate andelectrically connected to said first circuit pattern, resulting inprocessing an output of said pressure sensor element; a connectorincluding a connector body which is made of an insulating resin materialand includes a base having an end surface contacted with said frontsurface of said second insulating substrate of said pressure sensorelement and provided therein with a circuit component receiving chamberfor receiving said electric circuit component therein; said connectoralso including a plurality of connection conductors supported in saidconnector body and each having one end positioned in said circuitcomponent receiving chamber and the other end externally exposed; acircuit board arranged in said circuit component receiving chamber whilebeing kept spaced from said front surface of said second insulatingsubstrate and including a second circuit pattern electrically connectedto said first circuit pattern and connection conductors; electricalconnection means for electrically connecting said circuit board andfirst circuit pattern to each other; and a receiving casing made ofmetal and including a bottom wall section formed with a fluid inlet portfor introducing pressure measured fluid therethrough and a peripheralwall section connected at one end thereof to said bottom wall section;said receiving casing receiving said pressure sensor element and atleast a part of said base of said connector body therein so that a fluidchamber which said pressure measured fluid enters may be defined betweensaid pressure sensing surface of said pressure sensor element and saidbottom wall section; said circuit board being supported on a circuitboard support structure fixed on said second insulating substrate ofsaid pressure sensor element; said circuit board support structureacting also as said electrical connection means.
 16. A capacitance-typepressure sensor unit comprising: a pressure sensor element including afirst insulating substrate having a front surface provided thereon withan electrode and a rear surface acting as a pressure sensing surface anda second insulating substrate which has a rear surface provided thereonwith an electrode in a manner to be opposite to said electrode on saidfirst insulating substrate while being spaced at a predeterminedinterval therefrom and is combined with said first insulating substrate;a plurality of output electrodes formed on one of a front surface ofsaid second insulating substrate and a side surface thereof andelectrically connected to said electrodes; at least one electric circuitcomponent for processing an output of said pressure sensor element; aconnector including a connector body which is made of an insulatingresin material and includes a base having an end surface contacted withsaid front surface of said second insulating substrate of said pressuresensor element and provided therein with a circuit component receivingchamber for receiving said electric circuit component therein; saidconnector also including a plurality of connection conductors supportedin said connector body and each having one end positioned in saidcircuit component receiving chamber and the other end externallyexposed; a circuit board arranged in said circuit component receivingchamber while being kept spaced from said front surface of said secondinsulating substrate and including circuit patterns electricallyconnected to said output electrodes and connection conductors;electrical connection means for electrically connecting said circuitpatterns and output electrodes to each other; and a receiving casingmade of metal and including a bottom wall section formed with a fluidinlet port for introducing pressure measured fluid therethrough and aperipheral wall section connected at one end thereof to said bottom wallsection; said circuit board being formed with a plurality ofthrough-holes through which said connection conductors are inserted at adistal end thereof, resulting in being supported by said distal end ofeach of said connection conductors; said electrical connection meansincluding a plurality of metal terminal fitments each formed bysubjecting a flexible metal plate to machining; said terminal fitmentseach being provided at one end thereof with a first connection sectionformed with through-holes through which said connection conductors areinserted at said distal end thereof and connected to said distal end bysoldering and at the other end thereof with a second connection sectionwhich is fixed with respect to said second insulating substrate of saidpressure sensor element and connected to each of said output electrodesby soldering.
 17. A capacitance-type pressure sensor unit as defined inclaim 16, wherein said front surface of said second insulating substrateof said pressure sensor element is formed with a plurality of fit holesin each of which said second connection section of each of said metalterminal fitments is tightly fitted; said second connection section ofeach of said metal terminal fitments including a fit portion fitted ineach of said fit holes and a soldered portion arranged so as to extendalong said front surface of said second insulating substrate andconnected to said electrode section.
 18. A capacitance-type pressuresensor unit as defined in claim 16 or 17, wherein said metal terminalfitments are fixed on a single molded piece made of an insulating resinmaterial.
 19. A capacitance-type pressure sensor unit as defined inclaim 18, wherein said metal terminal fitments are insert-molded in saidmolded piece.
 20. A capacitance-type pressure sensor unit comprising: apressure sensor element including a first insulating substrate having afront surface provided thereon with an electrode and a rear surfaceacting as a pressure sensing surface and a second insulating substratewhich has a rear surface provided thereon with an electrode in a mannerto be opposite to said electrode on said first insulating substratewhile being spaced at a predetermined interval therefrom and is combinedwith said first insulating substrate; a first circuit pattern formed ona front surface of said second insulating substrate and electricallyconnected to said electrodes; at least one electric circuit componentarranged on the front surface of said second insulating substrate andelectrically connected to said first circuit pattern, resulting inprocessing an output of said pressure sensor element; a connectorincluding a connector body which is made of an insulating resin materialand includes a base having an end surface contacted with said frontsurface of said second insulating substrate of said pressure sensorelement and provided therein with a circuit component receiving chamberfor receiving said electric circuit component therein; said connectoralso including a plurality of connection conductors supported in saidconnector body and each having one end positioned in said circuitcomponent receiving chamber and an other end externally exposed; acircuit board arranged in said circuit component receiving chamber whilebeing kept spaced from said front surface of said second insulatingsubstrate and including a second circuit pattern electrically connectedto said first circuit pattern and connection conductors; electricalconnection means for electrically connecting said circuit board andfirst circuit pattern to each other; and a receiving casing made ofmetal and including a bottom wall section formed with a fluid inlet portfor introducing pressure measured fluid therethrough and a peripheralwall section connected at one end thereof to said bottom wall section;said receiving casing receiving said pressure sensor element and atleast a part of said base of said connector body therein so that a fluidchamber which said pressure measured fluid enters may be defined betweensaid pressure sensing surface of said pressure sensor element and saidbottom wall section; said circuit board being formed with a plurality ofthrough-holes via which said connection conductors are inserted at adistal end thereof, resulting in being supported by said distal end ofeach of said connection conductors; said electrical connection meansincluding a plurality of metal terminal fitments each formed bysubjecting a flexible metal plate to machining; said terminal fitmentseach being provided at one end thereof with a first connection sectionformed with through-holes via which said connection conductors areinserted at said distal end thereof and connected to said distal end bysoldering and at the other end thereof with a second connection sectionwhich is fixed with respect to said second insulating substrate of saidpressure sensor element and connected to an electrode section includedin said first circuit pattern by soldering.